A culture medium consisting of agar, peptone, and beef heart is classified as which type of medium?

• A. Selective medium
• B. Differential medium
• C. Defined medium
• D. Complex medium

Answer: (D)

Verified step by step guidance

1. Understand the components of the culture medium: agar, peptone, and beef heart. These ingredients are not chemically pure or precisely known in composition.
2. Recall the definitions of different types of culture media: a defined medium has exact known chemical composition; a selective medium contains agents that inhibit certain microbes; a differential medium allows differentiation between microbial types based on biochemical characteristics.
3. Recognize that peptone and beef heart extract are complex mixtures derived from natural sources, making the medium's exact chemical composition unknown.
4. Conclude that because the medium contains complex natural ingredients with unknown exact composition, it is classified as a complex medium.
5. Summarize that complex media are commonly used to support the growth of a wide variety of microorganisms due to their rich nutrient content.